A. Field of the Invention
The present invention generally relates to a new and improved system for controlling the kneeling operation on air suspension equipped transit vehicles such as buses.
B. Description of the Prior Art
One prior art means of assisting boarding by the elderly and handicapped onto transit vehicles such as buses, is to equip the transit vehicles with a system to allow the bus to kneel. The bus includes a driver activated kneeling system that lowers the front step height by releasing air from the front suspension air bags.
Although this system is satisfactory on transit vehicles without lifts, such a feature creates a problem on lift equipped vehicles of the type disclosed in U.S. Pat. No. 4,180,366, hereby fully incorporated by reference. For example, on high crowned roads, kneeling systems that activate only the front suspension element adjacent the door increases the transverse attitude of the vehicle beyond that due to the crown of the road thereby increasing the difficulty of obtaining a proper lift to curb interface and of maneuvering a wheel chair, for example, onto the lift and into the bus. Deploying the lift with prior art kneeling systems results in non uniform contact between lift extremities and the street surface, resulting in damage to the lift and/or difficulty in loading. For these reasons, most prior art kneeling systems do not permit simultaneous use of the lift and of the kneeling feature. It is desirable, therefore, to provide a system for controlling the kneeling of lift equipped transit vehicles.